For a cake the Germans call "the king of cakes" and the Japanese call "the ultimate wedding cake," the baumkuchen doesn't really look like a cake or behave like one. But it more than makes up for its oddities with rich flavor, history and symbolism.

It resembles a hollowed cross-section of a craggy tree trunk, or a planet's rings, depending on how you make it. It can have up to 21 delicate, sugary stratums, which give it a light yet chewy texture.

The crowning quality of this specialty cake is the unusual method of preparation. To make the nearly paper-thin layers, a baker coats a spit with sponge cake batter, mounts it over a heat source — originally an open fire, today in a specialized oven — and bakes it rotisserie-style, rotating the spit slowly until the first layer is baked. This process is repeated 12 to 20 more times until the spit forms the cylindrical core of the cake. Once cool, the cake is sliced into rings and slid off the spit.

The Germans lay claim to the baumkuchen, and have records of a recipe and a name — an amalgamation of baum (tree) and kuchen (cake) for the concentric rings of cake and tree — from the 15th century.

But the Germans may not have been the first to bake cakes in this fashion.

"There are references to making a cake on a log over fire from ancient Rome," says Heather Alcott, the owner of Glaze in Denver, one of only a few bakeries in the U.S. selling the treat. Alcott calls them baum cakes, and sells them along with cups of coffee and macaroons in her shop and through gourmet food stores.

Wherever the cake may have originated, it lingered in Europe until the 20th century, when it took Japan by storm thanks to a plucky prisoner of war. During World War I, the Japanese Army captured baker Karl Juchheim from his home in Tsingtao, China — which was under German control at the time — where he'd been operating a pastry shop.

In captivity, Juchheim baked baumkuchen for an exhibition staffed by war prisoners in 1919. When he was released a year later, he opened his first shop in Yokohama — the beginning of what would become a national craze.

The appeal of the cake is in its many layers. "The layers represent the accumulation of happiness, making it a strong icon of luck," says Sumimoto-San, a certified baumkuchenmeister in Japan. Sumimoto says the treat became popular in Japan thanks to a post-war environment in which people craved sweets, especially moist sponge cakes.

It was this passion for the baumkuchen that led Juchheim's former employees to open a shop in his honor. The shop became the Juchheim Group, which still exists today, operating under the slogan: "a faithful pursuit of authentic, delicious flavors."

It fueled the launch of numerous baumkuchen bakeries — from corner stores in train stations to high-end patisseries — and even led Japanese engineers to develop a specialized oven that allows for the simultaneous baking of up to 90 cakes at a time.

Glaze Bakery's Alcott got her hands on one of those ovens — eventually.

She first encountered the baumkuchen several years ago while living in Singapore, and fell in love with the texture and flavor.

After countless rebuffs from the Japanese oven manufacturing company, she finally convinced them to sell her their recipes and what she calls "The Red Dragon," a 2,200-pound, fire engine red baumkuchen oven — the first to operate outside Asia.

Now Glaze has taken the baum into uncharted territory. There are baums de Noël for Christmas and the Pumpkin Mount Baum, named one of the top U.S. pumpkin desserts by Food & Wine in 2013.

"I love that the art of the baumkuchen is one few know," says pastry chef Amanda Mueller, who has been with Glaze since it opened in 2013. She says the cake occasionally appears in her dreams, as do new flavor ideas — like orange fennel — and the sounding of timers, signifying it's time to add new layers of batter to the spits.